Disabled campaigners have welcomed a report by MPs on disability benefit assessments, which they say highlights “serious multiple failures”, but many believe it should have done more to highlight the serious “preventable harm” caused by the system.

It calls for “urgent change” in the system, including the introduction of routine recording of face-to-face assessments, and says that the government’s contractors, Atos, Capita and Maximus, “have consistently failed to meet basic performance standards”.

It also says the government should send every claimant a copy of the assessment report prepared by the healthcare professional who assessed them, which it says would “introduce essential transparency into decision-making”.

And it calls for improved accessibility of the system “at every stage” and pays tribute to the thousands of claimants who shared evidence with the committee, a response which it says was “unprecedented” for a select committee inquiry.

The committee concludes that the Department for Work and Pensions (DWP) should consider ending the outsourcing of the assessment contracts and bringing the assessment processes back in-house.

She said: “The report findings reflect what we hear every day from disabled people, that the assessment process is not fit for purpose, with poorly trained assessors and staggering levels of inaccuracy and dishonesty in the assessment reports.

“This not only results in a vast waste of taxpayers’ money, it also subjects disabled people to unacceptable levels of distress, placing considerable strain on our communities and on already over-stretched support services left trying to assist individuals through a process that is difficult to navigate and too often produces wrong and unfair decisions.

“This is yet further evidence that outsourcing to private providers is not only inefficient but that it’s the poorest people who are hit the worst by failings.”

Sue Bott, deputy chief executive of Disability Rights UK, said the “pervasive distrust in the system blights the claims process and creates misery for disabled people when they are in need of support.”

She said the committee’s calls to record face-to-face assessments and provide assessment reports to all claimants “would go some way to improving matters and we would strongly recommend the government implement those ideas as soon as possible”.

She said: “It’s ironic that so many disabled people are sanctioned within our benefits system when the assessment companies in the shape of Atos and Capita are making such a poor fist of doing what they are paid for – hundreds of millions of pounds of taxpayers’ money for a very poor service indeed.

“The government should, as the committee says, look closely at whether the assessment process should be brought in-house.

“Ultimately the government needs to completely overhaul what is a flawed system and replace it with one that identifies the true extra costs of living with disability, and is based on what disabled people can do with support rather than on what they can’t.”

But John McArdle, co-founder of Black Triangle, said he was “deeply dismayed” that Frank Field, the committee’s chair, had concluded that assessments “work adequately” for “the majority of claimants”.

McArdle said he believed that most claimants are harmed by the assessment process.

He also said the report had “not gone far enough” on the frequent failure of assessors and DWP decision-makers to collect further medical evidence (FME) about claimants.

Black Triangle is campaigning for a new legal duty on assessors and DWP decision-makers to seek FME for all ESA claimants with significant mental health conditions, including those with a history of suicidal thoughts and suicide attempts.

Last week, McArdle and fellow Black Triangle activist Maggie Zolobajluk met shadow chancellor John McDonnell to discuss what they hope will be a cross-party campaign.

McArdle said he was “shocked” that the report had ignored official government figures – passed to the committee by Disability News Service (DNS) – that suggest that the rate of lifetime attempted suicides among people claiming out-of-work disability benefits doubled between 2007 and 2014, following the introduction of the work capability assessment (WCA) in 2008.

He said: “We are flabbergasted that the committee has not confronted this reality and has not proposed concrete solutions on how to address it, in order to prevent further catastrophic avoidable harm as a result of this profoundly flawed disability assessment regime.”

McArdle is also frustrated that the report fails to mention evidence submitted to the committee that highlighted how the “biopsychosocial (BPS) model of disability”, which underpins the PIP assessment and the WCA, was “scientifically invalid”.

McArdle said the “ill-conceived” BPS model “has not even been touched upon by the committee”.

Mo Stewart, the disabled campaigner who spent years researching the “totally bogus” WCA for her book Cash Not Care: The Planned Demolition Of The UK Welfare State, was also highly critical of the committee for concluding that it was only a “minority of claimants who directly experience poor decision making”.

She said: “Following nine years of independent research on this subject, I have no idea how the work and pensions committee concluded that the identified preventable harm created by the WCA and PIP assessments only negatively impacts on a ‘minority of claimants’.”

She said the committee had “disregarded” the ongoing preventable harm caused by “the fatally flawed WCA”, particularly to people with mental health problems, some of which had been reported by the national media.

And she said: “Nowhere in the report does the work and pensions committee acknowledge the detailed evidence that the WCA and PIP assessments are based on the BPS model, as influenced by corporate American advisers, has no credibility, was designed to limit access to benefit and was totally discredited by independent research.”

Stewart added: “Whilst no doubt the recommended recording of assessments may help, the fact is that the use of the BPS model of assessment as used for both the WCA and PIP assessments was based on discredited DWP commissioned research, and its use should be abolished not amended.

“Trust in the assessments will not be returned so long as assessments which are fatally flawed by design continue to be used.”

Debbie Abrahams, Labour’s shadow work and pensions secretary, said the report “provides yet more damning evidence that these assessment processes are not fit for purpose and that trust in the system has been completely undermined under this government”.

She said: “Instead of supporting people, the process is often dehumanising, inaccurate and worsens existing health conditions.

“The widespread distrust of the assessment process by sick and disabled people is no surprise, with a record 68 per cent of decisions taken to tribunal being overturned by judges.

“Under private contractors the assessment process is getting worse, not better, yet the government refuses to act.”

She said Labour would scrap the current system, replacing it with “personalised, holistic support which provides each individual with a tailored plan, building on their strengths and addressing barriers, whether health, care, finance, skills, transport, or housing related”.

Stephen Lloyd, the Liberal Democrats’ spokesman on work and pensions, said the report was “utterly damning”.

He said: “It’s clear far too many assessments are inadequate for this system to continue in its current form.

“This is proof that the Liberal Democrat position of stripping the assessment contract from corporate behemoths such as Atos and Capita and bringing them in-house as a public service, is the only practical and humane way forward.”

A DWP spokeswoman said: “As the [committee]highlights, assessments work for the majority of people, with 83 per cent of ESA claimants and 76 per cent of PIP claimants telling us that they’re happy with their overall experience.

“However, our aim has to be that every person feels they are treated fairly, with respect and dignity.

“We are committed to continuously improving the experience of our claimants; that is why we’ve commissioned five independent reviews of the work capability assessment – accepting over 100 recommendations – and two independent reviews of PIP assessments.

“We continue to work closely with our providers to ensure people receive high quality assessments, and are exploring options around recordings to promote greater transparency and trust.”